Many engine vehicles recently include a variable valve timing mechanism which operates with a hydraulic pressure originating from motive power from an engine. The variable valve timing mechanism varies timing of opening and closing of an intake valve (or an exhaust valve) by varying a rotation phase of an intake cam (or an exhaust cam) with respect to a crankshaft. In general, this variable valve timing mechanism is provided with a locking mechanism for holding an intake cam at a greatest-retard position when the engine is stopped while the intake cam is at the greatest-retard position (in the exhaust cam, the greatest-advance position). Then, before the engine is stopped, greatest-retard control for returning the intake cam to the greatest-retard position is carried out. As a result of this greatest-retard control, the intake cam is held at the greatest-retard position by the locking mechanism at the time when the engine is started next time (at the time of cranking), and hence vibration of the variable valve timing mechanism at the time when the engine is started is prevented.
Japanese Patent Laying-Open No. 2000-213383 (PTL 1) discloses a technique for starting greatest-retard control above after motor regenerative control is started and stopping an engine at the time point when a sensor subsequently detects return of an intake cam to a greatest-retard position in a hybrid vehicle including as one motive power source, the engine provided with a variable valve timing mechanism configured to be able to vary timing of opening and closing of an intake valve. According to this technique, since the engine is stopped at the time point when the sensor detects return of the intake cam to the greatest-retard position, the intake cam can return to the greatest-retard position before the engine stops.
In addition, PTL 1 also discloses a technique for stopping the engine based on estimation that the intake cam returned to the greatest-retard position at the time point when a predetermined delay time has elapsed since start of greatest-retard control, instead of detection by the sensor of return of the intake cam to the greatest-retard position.